SpaceX plans the first launch of the world's most powerful rocket from Kennedy Space Center later this month, but first, there is a test firing today (Thursday).
The 230-foot Falcon Heavy will be loaded with fuel and its 27 Merlin engines fired for the first time.
That is scheduled to happen sometime during a six-hour window from 1 p.m. to 7 p.m. Eastern time.
SpaceX says the Falcon Heavy will blast off on a demonstration flight sometime around the end of January with a payload containing CEO Elon Musk's 2008 Tesla Roadster.